GLOSSARY. 163 



Crustacea (Lat. crusta, a crust) A class of Annulosa, including 

 crabs, lobsters, &c. They are so called because they are 

 covered with a shell or hard crust. 



Ctenoid (Gr. kteis, a comb; eidos, form) A term applied to the 

 scales of fishes which have comb-like margins. 



Ctenophora (Gr. kteis, a comb; phero, I bear) A group of Actino- 

 zoa, whose swimming organs consist of comb-like bands of cilia. 



Cursores (Lat. curro, I run) An order of birds, including the 

 ostrich, emeu, cassowary, and rhea, which are destitute of 

 the power of flight, 

 i Cuticle (Lat. cutis, the skin) The outer layer of the skin. 



Cycloid (Gr. kuklos, a circle; eidos, form) A term applied to cir- 

 cular fish scales. 



Cyst (Gr. kustis, a bladder) A bladder-like sac. 



Dermal (Gr. derma, skin) Belonging to the skin. 

 Diaphragm (Gr. diaphragma, a partition) The muscle which 



separates the thorax from the abdomen in the Mammalia. 

 Diatomaceae (Gr. diatemno, I cut asunder) A group of microscopic 



plants, provided with siliceous coverings. 

 Dibranchiata (Gr. dis, twice ; branchiae, gills) The cuttle-fish 



tribe, so called because they possess two gills. 

 t Didelphia (dis, twice ; delphus, the womb) The marsupial 



mammals. 



Digit (Lat. digitus, a finger) A finger or toe. 

 Dorsal (Lat. dorsum, the back) Belonging to the back. 



Echinodermata (Gr. echinos, a hedgehog; derma, skin) A class of 

 animals, including the sea-urchins and star-fishes. It is so 

 called on account of the spines with which the integument 

 is generally furnished. 



. Ectocyst (Gr. ektos, without; kustis, a bladder) The outer cover- 

 ing of the Poly zoa. 



Ectosarc (Gr. ektos, without; sarx, flesh) The outer layer of 

 sarcode in the Amoeba. 



Elytra (Gr. elytron, a sheath) The horny front pair of wings in 

 beetles, which form a case for the protection of the mem- 

 branous pair. 



Embryo (Gr. en, in ; bruo, I swell) The earliest stage in which 

 an animal may be discerned in the egg. 



Encrinite (Gr. kryion, a lily) The "stone lily,'* a group of 

 Echinodermata. 



Encystment (Gr. kustis, a bladder) A change undergone by some 

 of the Protozoa, in which they become motionless, and cover 

 themselves with a " cyst" or sac. 



Endocyst (Gr. endon, within; kustis) The inner layer of the 

 Polyzoa. 



